The present disclosure relates to an image forming apparatus such as a copier or a multifunction peripheral, and in particular relates to an image forming apparatus including a photoconductor drum used in a process of forming an image on a sheet.
An image forming apparatus of an electrophotographic system includes a photoconductor drum on which a toner image is formed by a developing device. The toner image formed on the photoconductor drum is transferred to a transfer belt by a primary transfer device, and is further transferred from the transfer belt to a sheet by a secondary transfer device. The photoconductor drum is unitized into a drum unit together with a frame and the like, wherein the frame rotatably supports the photoconductor drum. The drum unit including the photoconductor drum is attached to the image forming apparatus in a detachable manner. There is known, as one example of conventional image forming apparatuses, an image forming apparatus to/from which the drum unit is inserted and pulled out horizontally.
As one example of such drum units, there is known a drum unit that includes a flange fixed to an end portion of the photoconductor drum in the axial direction. The flange is integrally formed with a gear portion that transmits a rotational driving force to another driven body.